Hi Prese,
To start, whatever materials you do use, I would also incorporate presentation and fluency skills. If the students must present their PhDs at some point in the future, the ability to speak smoothly, coherently, and with well-ordered thoughts will be very important. I don't know where you are teaching, but remember that some cultures structure essays/information differently.
I would also try to use real material that gives them the chance to use information/ideas that may come up in the PhD presentation. Short articles from news sites work very well, as this will allow a jumping off point on the topic. Don't select a long article that becomes a lesson on translation without any opportunity for discussion.
Take a look at my news site for ESL / EFL students as a starting point:
English Lesson Plans | Heads Up English | ESL Lessons
Good luck!